Question

What is electrical resistivity? In a series of electrical circuits comprising a resistor made up of a metallic wire, the ammeter reads 5 A. The reading of the ammeter decreases to half when the length of the wire is doubled. Why?

Answer 1

• Property of the conductor which resists the flow of electric current is called resistivity. 
• Resistance for a particular material is unique. 
• Resistance is directly proportional to length of conductor and inversely proportional to current flow. 
• When length is doubled resistance becomes double and current flow reduces to half. 
• This is the reason for the decrease in ammeter reading.